diff --git a/mathlib.c b/mathlib.c
index 8c71eabb..f0e84b98 100644
--- a/mathlib.c
+++ b/mathlib.c
@@ -3,7 +3,7 @@
 ** Mathematics library to LUA
 */
 
-char *rcs_mathlib="$Id: mathlib.c,v 1.3 1994/08/15 14:13:44 celes Exp celes $";
+char *rcs_mathlib="$Id: mathlib.c,v 1.4 1994/10/11 13:06:47 celes Exp roberto $";
 
 #include <stdio.h>		/* NULL */
 #include <math.h>
@@ -160,16 +160,27 @@ static void math_sqrt (void)
  lua_pushnumber (sqrt(d));
 }
 
+static int old_pow;
+
 static void math_pow (void)
 {
- double d1, d2;
  lua_Object o1 = lua_getparam (1);
  lua_Object o2 = lua_getparam (2);
- if (!lua_isnumber(o1) || !lua_isnumber(o2))
- { lua_error ("incorrect arguments to function `pow'"); return; }
- d1 = lua_getnumber(o1);
- d2 = lua_getnumber(o2);
- lua_pushnumber (pow(d1,d2));
+ lua_Object op = lua_getparam(3);
+ if (!lua_isnumber(o1) || !lua_isnumber(o2) || *(lua_getstring(op)) != 'p')
+ {
+   lua_pushobject(o1);
+   lua_pushobject(o2);
+   lua_pushobject(op);
+   if (lua_callfunction(lua_getlocked(old_pow)) != 0)
+     lua_error(NULL);
+ }
+ else
+ {
+   double d1 = lua_getnumber(o1);
+   double d2 = lua_getnumber(o2);
+   lua_pushnumber (pow(d1,d2));
+ }
 }
 
 static void math_min (void)
@@ -292,7 +303,6 @@ void mathlib_open (void)
  lua_register ("floor", math_floor);
  lua_register ("mod",   math_mod);
  lua_register ("sqrt",  math_sqrt);
- lua_register ("pow",   math_pow);
  lua_register ("min",   math_min);
  lua_register ("max",   math_max);
  lua_register ("log",   math_log);
@@ -300,4 +310,5 @@ void mathlib_open (void)
  lua_register ("exp",   math_exp);
  lua_register ("deg",   math_deg);
  lua_register ("rad",   math_rad);
+ old_pow = lua_lock(lua_setfallback("arith", math_pow));
 }
diff --git a/opcode.c b/opcode.c
index 11816826..9dfcab63 100644
--- a/opcode.c
+++ b/opcode.c
@@ -3,7 +3,7 @@
 ** TecCGraf - PUC-Rio
 */
 
-char *rcs_opcode="$Id: opcode.c,v 3.14 1994/11/17 13:58:57 roberto Exp roberto $";
+char *rcs_opcode="$Id: opcode.c,v 3.15 1994/11/17 16:41:42 roberto Exp roberto $";
 
 #include <setjmp.h>
 #include <stdio.h>
@@ -69,7 +69,7 @@ static void lua_message (char *s)
 */
 void lua_error (char *s)
 {
-  lua_message(s);
+  if (s) lua_message(s);
   if (errorJmp)
     longjmp(*errorJmp, 1);
   else
@@ -877,19 +877,19 @@ static int lua_execute (Byte *pc, int base)
    break;
 
     case LTOP:
-      comparison(LUA_T_NUMBER, LUA_T_NIL, LUA_T_NIL, "<");
+      comparison(LUA_T_NUMBER, LUA_T_NIL, LUA_T_NIL, "lt");
       break;
 
    case LEOP:
-      comparison(LUA_T_NUMBER, LUA_T_NUMBER, LUA_T_NIL, "<=");
+      comparison(LUA_T_NUMBER, LUA_T_NUMBER, LUA_T_NIL, "le");
       break;
 
    case GTOP:
-      comparison(LUA_T_NIL, LUA_T_NIL, LUA_T_NUMBER, ">");
+      comparison(LUA_T_NIL, LUA_T_NIL, LUA_T_NUMBER, "gt");
       break;
 
    case GEOP:
-      comparison(LUA_T_NIL, LUA_T_NUMBER, LUA_T_NUMBER, ">=");
+      comparison(LUA_T_NIL, LUA_T_NUMBER, LUA_T_NUMBER, "ge");
       break;
 
    case ADDOP:
@@ -897,7 +897,7 @@ static int lua_execute (Byte *pc, int base)
     Object *l = top-2;
     Object *r = top-1;
     if (tonumber(r) || tonumber(l))
-      call_arith("+");
+      call_arith("add");
     else
     {
       nvalue(l) += nvalue(r);
@@ -911,7 +911,7 @@ static int lua_execute (Byte *pc, int base)
     Object *l = top-2;
     Object *r = top-1;
     if (tonumber(r) || tonumber(l))
-      call_arith("-");
+      call_arith("sub");
     else
     {
       nvalue(l) -= nvalue(r);
@@ -925,7 +925,7 @@ static int lua_execute (Byte *pc, int base)
     Object *l = top-2;
     Object *r = top-1;
     if (tonumber(r) || tonumber(l))
-      call_arith("*");
+      call_arith("mul");
     else
     {
       nvalue(l) *= nvalue(r);
@@ -939,7 +939,7 @@ static int lua_execute (Byte *pc, int base)
     Object *l = top-2;
     Object *r = top-1;
     if (tonumber(r) || tonumber(l))
-      call_arith("/");
+      call_arith("div");
     else
     {
       nvalue(l) /= nvalue(r);
@@ -949,18 +949,8 @@ static int lua_execute (Byte *pc, int base)
    break;
 
    case POWOP:
-   {
-    Object *l = top-2;
-    Object *r = top-1;
-    if (tonumber(r) || tonumber(l))
-      call_arith("^");
-    else
-    {
-      nvalue(l) = pow(nvalue(l), nvalue(r));
-      --top;
-    }
-   }
-   break;
+    call_arith("pow");
+    break;
 
    case CONCOP:
    {